When you think power supply for a computer is a lot different than a power supply for a server. For a server it comes in different sizes to match the size of the server chassis. As for a computer the most common is a form factor ATX. For smaller power supplies they measure in size like the SFX, Flex ATX or TFX. When it comes to server sizes, 1u will have its own 1u power supply size. Anything above that should be able to use a standard ATX power supply that's cable modular or not. Server grade power supply can also be redundant. In a single PSU housing it can have 2 modules which equal the same amount of wattage deliverance to the server. If one fails the other proceeds to give power to the server. These are mostly more expensive than a standard ATX power supply. There is nothing wrong with using a standard ATX power supply for server use.